Security attachment for cylinder lock



Oct. 6, 1970 E. WEBER 3,531,959

SECURITY ATTACHMENT FOR CYLINDER LOCK Filed Sept. 5, 1968 INVENTOR [an 4w (die/5e Irma/1K5 United States Patent 3,531,959 SECURITY ATTACHMENT FOR CYLINDER LOCK Edward Weber, 5867 Auburn Blvd., Sacramento, Calif. 95841 Filed Sept. 5, 1968, Ser. No. 757,613 Int. Cl. Eb 27/02 Cl. 70364 3 Claims ABSTRACT OF THE DHSCLOSURE In the bottom of the keyway of a lock cylinder there is formed an enlarged chamber capable of receiving a small metal ball. In the body of the lock encompassing the cylinder is a segmental groove having a depth about equal to the ball radius and having a ramp at one end. A portion of the groove is in registry with the ball in the enlarged chamber in the cylinder in beginning position. Thus the porper key can be inserted in the keyway and the cylinder rotated until the ball, carried along the groove by the rotating cylinder, encounters the ramp. At this juncture the ball is cammed up the ramp until it abuts the key. The key must thereupon be removed to allow further rotation of the cylinder into operative position. An exterior handle on the cylinder is rotated to return the cylinder and the ball to base position.

The invention relates generally to improvements in cylinder lock attachments and, more particularly, to ignition lock attachments which are eifetcive to turn on the ignition switch only if the correct ignition key is used and only if the ignition key is removed from the lock at a predetermined juncture prior to the time the switch is closed.

It is Widely known in law enforcement fields that one of the major causes of car thefts is the carelessness of the driver in leaving the key in the ignition switch while the car is unattended.

Many devices have been developed to try to counteract this undesirable habit. Most of such devices have been of the audio-visual warning type which become operable, for example, when the driver fails to remove the key and opens the door to leave the car. Such mechanisms have served moderately well but depend for the most part on electrical components which are somewhat costly and which inevitably become corroded or otherwise wear out.

It is therefore an object of the invention to provide a security attachment for a cylinder lock which is entirely mechanical in nature and which is as long-lived and reliable as the cylinder lock itself.

It is another object of the invention to provide an attachment which enhances the safety features of all types of cylinder locks, but which is of particular value when used in conection with ignition switch locks of the kind used in motor vehicles.

It is a further object of the invention to provide a lock attachment which is economical and fool-proof.

It is another object of the invention to provide a generally imroved security attachment for a cylinder lock.

Other objects, together with the foregoing, are attained in the embodiment described in the following description, and illustrated in the accompanying drawings in which:

FIG. 1 is a fragmentary front perspective view of a vehicle dashboard, showing the external handle portion of the attachment on an ignition switch lock;

FIG. 2 is a fragmentary median, vertical, longitudinal sectional view;

FIG. 3 is a transverse sectional view showing the parts in beginning position, the plane of the section being indicated by the line 33 in FIG. 2;

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FIG. 4 is a view comparable to that of FIG. 3, but showing the parts in final position; and

FIG. 5 is a side elevational view of a key modified by the formation of a semicircular recess on the bottom edge to extend the keys capabilities.

While the lock attachment of the invention is susceptible of numerous physical embodiments depending upon the environment and requirements of use, substantial numbers of the herein shown and described embodiment have been made, tested and used, and all have performed in an eminently satisfactory manner.

The lock attachment of the invention, generally designated by the reference numeral 12, lends itself to use in substantially any kind of cylinder lock, but is of espeical utiilty in ignition switch locks located, for example, on the dashboard 13 of a motor vehicle.

In the embodiment disclosed herein the only external member is a circular plate 14, or escutcheon, formed with a pair of oppositely projecting handles 16 affording the driver a convenient moment arm to rotate the escutcheon 14 at the appropriate junctures, as will be described.

The escutcheon plate 14 is mounted on the outer end of a lock cylinder 21, or plug, rotatably mounted in an annular lock body 23 having an upwardly projecting elongated block portion 24 formed with a plurality of vertical, cylindrical recesses 26, 27 and 28. The vertical axes of the recesses lie in the median vertical plane 29 of the cylinder 21 (see FIGS. 3 and 4).

Vertically reciprocable in the recesses 26,27 and 28, are upper pin tumblers 36, 37 and 38, respectively. The pins are biased downwardly by compression springs 41, 42 and 43, respectively, the upper ends of the springs being confined by suitable caps 44, or closure plugs, mounted in the tops of the recesses.

A housing 46 encompasses the lock, the housing being secured to the back side of the dashboard as by welded flanges 47 (see FIG. 2).

The cylinder 21 is restrained against outward movement by a keeper 48, and extending from the inner end of the cylinder is an operating member 49 utilized either to operate a latch bolt or an ignition switch contact, neither of which item is shown herein, being of conventional make.

The operating member 49 is actuated by rotation of a key 50 inserted within avertical keyway 51. The key 50 has a conventional cross-section and is provided with the customary upstanding lugs 52, 53 and 54 of variable height and arranged in a predetermined fashion to cooperate with lower pin tumblers 56, 57 and 58, respectively.

The lower pin tumblers 56, 57 and 58 translate in throughbores 61, 62 and 63, respectively, formed radially in the cylinder 21.

In the base, or initial, position, as appears most clearly in FIGS. 1, 2 and 3, the key lugs 52, 53 and 54 are of the correct size and sequence with respect to the lower pin tumblers 56, 57 and 58. Consequently, the interfaces 66 67 and 68 shared by the three sets of pin tumblers are in alignment with the periphery of the cylinder (see FIGS.

2 and 3) and therefore the pins oifer no significant resistance to rotation of the key 50, the cylinder 21 and the operating member 49.

As the cylinder begins to move away from the base position shown in FIG. 1, 2, and 3, the cylinder carries, or urges, along with it a small metal ball 71 such as a ball bearing. The upper part of the ball is located in the bottom of a slightly vertically elongated but substantially hemispherical chamber 72 formed in the bottom of the cylinder opposite the lower pin tumbler 56 (see FIGS. 2 and 3). The chamber 72 opens upwardly to the keyway 51 and therefore receives a portion 74 of the lower edge 76 of the key 50.

The bottom part of the ball 71 is disposed within a circumferential segmental groove 77 formed in the lock body, the groove extending (see FIG. 3) from a vertical wall 78 at approximately 5 :30 oclock to an inclined ramp portion 79 commencing at about 6:30 oclock and extending toward the left and upwardly, terminating at the interface 81 between the lock cylinder and the lock body at about a 7:00 oclock location.

The groove 77 has a depth approximately equal to the radius of the ball 71. Thus, about one-half the ball projects upwardly into the slightly vertically elongated but generally hemispherical chamber 72. A lip 83 (see FIG. 3) formed by the intersection of the chamber 72 and the cylinder periphery engages the ball 71 at about the balls equator. Consequently, as previously stated, the lip urges the ball along the groove, to the left (FIG. 3) and away from the vertical boundary wall 78, as the key rotates the cylinder in a clockwise direction, this being the direction customarily followed in turning on an ignition switch.

As appears most clearly in FIG. 3, the bottom edge of the key, as at 74, is spaced apart from the bottom path of the groove 77 a distance just slightly in excess of the ball diameter.

Therefore, when the cylinder 21 is rotated in a clockwise direction through about 25 of arc, so that the initially vertical plane 29 assumes the new attitude indicated by the plane 86 (see FIGS. 3 and 4) further rotation is rendered impossible unless the key is extracted from the lock.

In other words, with the key in the angular attitude of the plane 86, the ball 71 has been brought into abutment with the bottom of the ramp 79. Any further rotation at this juncture urges the ball upwardly against the adjacent bottom 74 of the key and rotation is halted.

As the driver feels this resistance to further rotation, the key 50 is removed, and concurrently, the fingers are used to grip the handles 16 and continue rotation. Removal of the key allows the ball to move upwardly into the chamber 72 (see FIG. 4) as the ball travels up the ramp '79 under the urgency of the cylinder lip 83.

Upon reaching the top of the ramp, the ball 71 is fully lodged within the hemispherical chamber 72 and the plane of the keyway and ball is approximately as indicated by the reference numeral 88 in FIG. 4.

A slight additional clockwise rotation is effective to close the ignition switch terminals (not shown) thus starting the vehicles engine.

The key 50, having been extracted, is now preferably placed in the drivers pocket, or purse, for safekeeping.

When the vehicle has come to a stop and the engine is to be turned off, the driver takes hold of the handles 16 and rotates the cylinder in a counterclockwise direction, thereby opening the ignition switch and stopping the engine.

As the ball 71 is urged counter-clockwise and reaches the ramp 79 it moves downwardly by gravity as it traverses the ramp. The trailing wall of the hemispherical chamber 72 concurrently urges the ball toward and ultimately brings the ball into abutment with the vertical boundary wall 78. At this juncture, the ball, the keyway and the cylinder have all resumed their initial positions and the device has completed its cycle.

FIG. 5 illustrates a variant form of key 150 which differs from the key 50 only in the fact that the bottom edge 176 of the key 150 has formed therein a semi-circular recess 174 which registers with the profile of the hemispherical chamber 72, as this chamber appea s in broken line in FIG. 2. The recess 174 in other words, prevents interference from taking place between the ball 71 and the key portion 74 as the ball is being cammed up the ramp 79. This means that the key 150 need not be removed from the lock in order to effect full closure of the ignition switch.

It can therefore be seen that I have provided an economical, yet foolproof and convenient security attachmeent for a cylinder lock.

What is claimed is:

1. A security attachment for a cylinder lock having a body formed with a plurality of recesses; cylinder rotatably disposed within the lock body and including a longitudinal keyway connecting with a plurality of radial throughbores arranged for registry with the body recesses in a predetermined angular position of the cylinder; and a plurality of upper and lower pin tumblers slidably disposed in the recess and throughbores, respectively, the upper pin tumblers being spring-urged toward the cylinder, and the lower pin tumblers each being of a pre determined length such that a predetermined key inserted against the lower pin tumblers is effective to position the junction of the upper and lower pin tumblers in registry with the outer periphery of the cylinder to permit rotation thereof, said attachment comprising:

(a) a handle mounted on the cylinder for selective rotation of the cylinder; and,

(b) a ball movable between a first position wherein said ball is located partially within a chamber in said cylinder, said chamber opening into said keyway, and partially within a segmental groove formed in the lock body, and a second position wherein said ball is located entirely within said chamber, said key being effective to prevent movement of said ball into said chamber until said key is removed from said keyway as said ball is moved by the walls of said chamber from said first position partially toward said second position, removal of said key affording free ingress of said ball into said chamber and permitting subsequent movement to said second position.

2. An attachment for a lock cylinder as in claim 1 wherein one end of said groove is defined by a substantially radial boundary wall limiting the movement of said ball, and the other end of said groove is defined by a ramp urging said ball entirely into said chamber as the cylinder is rotated carrying said ball in a direction from said boundary wall toward and onto said ramp.

3. A device as in claim 2 wherein said handle includes a pair of moment arm members mounted on the outer end of the cylinder.

References Cited UNITED STATES PATENTS 1,334,292 3/1920 Cox 216 XR 1,669,115 5/1928 Anakin 70-421 XR 1,835,725 12/ 1931 Thompson, et a1. 70 421 XR 3,418,833 12/1968 Kerr 70-421 MARVIN A. CHAMPION, Primary Examiner R. L. WOLFE, Assistant Examiner U.S. Cl. X.R. 

